Take-off system for rotative winged aircraft



May 4, 1948.

H. F. PITCAIRN TAKE-OFF SYSTEM FOR ROTATIVE WINGD AIRCRAFT Filed March 9, 1945 3 Sheets-Sheet 1 ATTOR NE V5 H. F. PITCAIRN 2,440,758

May 4,4 1948.

TAKE-OFF SYSTEM FOR ROTATIVE WINGED AIRCRAFT 3 Sheets-Sheet 2 Filed March 9, 1945 IN NTOR. M

ATTORNEYS May 4, i948. H. F; PITCAIRN TAKE-OFF SYSTEM FOR ROTATIVE WINGED AIRCRAFT Filed March 9, 1945 s sheets-shea 3 Alma ci.

m 7 R. m r 6 0 E MW w l T N A V Y 0 m H 01| Patented May 4, 1948 TAKE-OFF SYSTEM FOR ROTATIVE WINGEB AIRCRAF Harold F. Pitcairn, Bryn Athyn, la., assignorto Autogiro Company of America, Philadelphia, Pa., a corporation of Delaware Application March 9, 1945, Serial No. 581,789

This invention relates to rotative winged aircraft and is particularly concerned with a system for effecting take-off of such aircraft.

Although various features of the invention are adapted to use in association with any rotor equipped aircraft, whether or not the rotor is power driven in normal flight, the invention is of particular applicability to that type of aircraft incorporating a sustaining rotor capable of aerodynamic or autorotational actuation during at least some phases of normal flight operation. In a typical aircraft incorporating an autorotatable sustaining rotor, a single multi-bladed rotor is mounted in a position generally centralized over the center of gravity of the aircraft, the aircraft further being provided with one or more `propulsive airscrews adapted to effect translational flight, the :airscrews being driven by one or more engines mounted on the aircraft. The sustaining rotor in such aircraft is kept in motion by Virtue of the airflow across the blades of the rotor, as set up either by translational flight, or in gliding or vertical descent without power.

Several methods for effecting take-off of this type of aircraft are already known, including preliminarily driving the rotor from an engine thereon while the aircraft is on the ground and then disconnecting the power drive and effecting take-off following a take-oir run. In accordance with another known system, the rotor blade pitch angle is reduced to a non-lifting value and the rotor is power driven from an engine on theaircraft while the machine is on the ground,Y the R. P. M. initially imparted being higher than the normal flight R. P. M., so as to store excess kinetic energy in the rotor. When take-off is desired the power drive is disconnected from the rotor and the pitch angle of the rapidly rotating rotor blades is increased and the excess kinetic energy stored in the rotor is converted to lift, thereby causing the aircraft to rise vertically or substantially vertically from the ground, following which (or during which) the propulsive airscrew or airscrews establish translational flight.

Both of the take-off systems just described require that relatively heavy and complicated'power transmission mechanism be built into the Inachine.

On the other hand the present invention contemplates employment of a take-off system which utilizes a power source external to the aircraft and not carried thereby, the system of the present invention being capable of effecting substantially vertical take-olf. In this way the advantages of substantially vertical take-off are achieved while 13v Claims. (Cl. 244-17) avoiding some of the disadvantages of prior practice, including the necessity for carryingpower transmission mechanism between an engine on the aircraft and the rotor hub.

More specifically, the invention contemplates temporary coupling of a power source on the ground with the aircraft, as by means of a flexible power transmission arranged to acceler'atethe rotor up to a suitable take-off speed and preferably to continue driving the rotorV during the course of the take-off, for which purpose the flexible power transmission is extensible. When the desired elevation from the ground has been attained, the power transmission is disconnected, and translational iiight established by the propulsive airscrew or airscrews.

Another object of the invention is the employment of a rotor drive system which is non-reactive, i. e., a system for driving the rotor which does not tend to cause the body of the aircraft to rotate in the opposite direction, as is the case with mechanical drive systems interconnecting the rotor hub and an engine mounted on the aircraft. In this way the employment of special means for counteracting rotor driving torque (such as the helicopter type of anti-torque rotor at the tail of the machine rotating about a hori- Zonta] axis), is obviated.

For the above purpose the invention contemplates equipping the rotor blades with jet reaction devices and, as a source of power on the ground, utilizing an appropriate fluid pressure power source, in which case the power transmission which is adapted to be temporarily coupled with the aircraft for take-off takes the form of a flexible fluid pressure connection.

As an additional object, the invention provides, in a system of the type above mentioned, pilot operable control means on the aircraft for disconnecting the power transmission when the take-olf has been completed; also :automatic mechanism for paying-out the flexible power transmission during the course of the take-olf; automatic mechanism ,for reeling-in the flexible power transmission after the same has been discon. nected from the aircraft; and means providing automatically for shut-off of power through the iiexible transmission, when the transmission has been disconnected from the aircraft following a take-off. T

The foregoing and other objects and advantages of the invention will appear more fully following a description of the accompanying drawings in which- Figure 1 is a somewhat schematic View il1us.

trating an aircraft of the type above mentioned standing on the ground above a chamber in which various parts of the power transmission and control mechanism for the take-01T are arranged, this view also showing in chain dotted lines a second position of the aircraft during the course of -a take-on;

Figure2isfan enlarged'view partlyin vertical section and partly in elevation illustrating various features of the take-off system of the presentV invention;

Figure 3 is an axial vertical sectional view through a suitable reel and a uid pressure type power transmission, as employedfinfthe arrangement of Figures 1 and 2;

Figure 4 is an elevational view of a modified form of power transmission in--whichiiuidpressure connections are employed in a telescopic arrangement;

Figure 5 is an enlarged vertical sectional view through :a portion.` of :the .mechanism=.o.f.:Figgure 1.4; and

Figures 6 `and..4 7' are :verticalsectional-.views of upper and lower end portionsof .the telescopic fluidl vpressure connections 'of .Figure '.4'.

In :Figure 1 'the aircraft comprises a Ybfoidy 1.8, over iwhich :a sustaining rotor is mounted .incorporating blades dfconnectedwithahu'b im which latter is'mounted by meansof .apylon'structure Il. In-'tlie machine illustratedpusher-typeiprm pulsive V-airscrews l2 are employed, one fbeing mounted toward each side `of 'the'bod-y, v-as by an -outrigger t3 .which alsoserves Ito carryf one o'f fthe main -landing :wheels M. The ,'airscrews i'2`11nay `be .driven :from a power .plant .'(not shown) within the body, :as bymeansof .power drive shafts extended ythrough the `outriggers 1. I 3. Av-'nose Elanding `wheel t5 iis also .indicated in Figure c1. Toward 'the `rear end-of Lthe .body 'B an empennage is provided including Ahorizontal stabilizersurfacing fit, Vvertical fins ill .and .rudders i8 itrailing the vertical inns tl.

As shown in EFigure 1,the` aircraft is illustrated substantially in outline, sin'cezthe `general structure `of the `aircraft Aitself .forms no part of the present invention per se. Several factors of -importan'ce should, however, be noted, lincluding r the following:

It iis contemplated Lthat 4each rotor blade 9 be connected with the rotative hub 'by :pivotal mountings providing at leastsome freedom for blad'efswinging movement in directions transverse the mean '.rotative path-of v`travel so as `to Yaccorrunodate differential -ight forces during translational flight. In addition, it lis contemplated that the vrotor blades be `mounted-von the hub with `freedom for .pitchvchange 4movement and that -a control means be Vprovidedffor simultaneously raising and 'lowering the pitch of all of'the'blades, whereby to vary the thrust of the rotor :and A`provide Vfor increasingthe thrust when .itis-'desired to ltake-o'fffrom the ground. 'Some known Iform of rotore control iis 'alsocontemplated such 'fforexample as Ycontrol by tilting the v`rotor hub,-as disclosed, .for instance 'in vcopendirrg 'applicationpf ."Juan dela CerVaJSerial No'. '645;985, ledwfDecember 6, 1932i (issued `as Patent 2,386,580), or :control by cyclicall-y .varying the rotorblade pitch-.angles 'aszdisclos'ed forzinstance, in copending application of Juan de la Cierva, Seria'lLNo. 698,37 2,1nled November 715, .1;933-(.iss11ed as `liatgent 12,389 582). Since ,rotor fbl'a'de :mount-4 ings providing .the .functions referred :to 'above are known in the art (for example in said PatentV 2,380,582 and Vcorresponding British Patent 410,532), no speciic disclosure thereof is given herein. Y

As above mentioned, the rotor blades are preferably equipped with jet reaction nozzles I8 to which jet reaction fluid, such as compressed air, steam or the like is supplied through the blades themselves, and through the hub, from a uid pressure connection 2e which extends downwardly through the pylon to a point adjacent the .bottom or floor 8a of the body 8. The arrange- .ment `lof vhub andblade mounting parts providing `for"transmission of `fluid therethrough forms no part of the present invention per se, Vbut it is noted .that `suitable mechanism of this type is :disclosed-in copending application of C. G. Pullin,

Serial No. "484,964, `led April 22, 1943 (and in corresponding VBritish Patent 557,011). As is brought out below, the fluid pressure connection 2d :is vadapted to be coupled with the flexible power transmission for receiving the jet operating fuid therefrom.

:As shown in lFigure 1, the .aircraft i-s at :rest on the ground -Cnarchamber` 2.1 Vbeingprovided below the surface andclosedby a cover plate 22. In connection with Ithis .showingwit will be understood that the .equipment and systemof the present yinvention are v applicable to other. situations,.for instance to landing and ktake-oil platforms on.ships,on the roofs of.buildings,..or the like-and the .word ground intheclaims is-thus tofbe .broadly understood.

In .the embodiment of .Figures 1 to 3, the power transmission which is extensible and retractable takes the form of a flexible -hose .23 associated with .a drum Ytypereel 24 (seeFigure 3) Arotatively mounted by standards25-2 5. `One end .of the hose .23 vis extendedinwardly through' an aperture in the drum wall vof the reel for connection .with achamber 26, with which chamber .the fluid pressure supply line 2l also communicates, this supply line being arranged coaxi-ally with the .axis of the reel andbeing extended through one vof .the .mounting bearings therefor. Pressure vleakage is avoidedby employmentof a stufng boX.28 of Vknown type.

The reel 24- is adapted to be driven from the electric Ymotor 29 through `reduction gearing 30 and ,afbeltvor .chain drive 3.I, which latter cooperates with a pulley or .sprocket 32amounted `on the reel shaft `33 and adapted to be drvingly connected with said shaft 33 through a torque limiting clutch 34. The torque limiting clutch preferably yis constructed to-operate in either-direction, vasby employing spring pressed friction plates. The .motor 29 is vof the type capable of operationin either-direction, soas to :eiect rotation of (thereel either to pay-out or reel-in the h'ose 23.

A serieslof guide rollers 35 is .arranged about thecircumference o1 the reel, each roller being rotative about its own axis but the .series being -xed as against rotation about the axis'of the reel. .These rollers serve .to keep .the hose .in proper position on the reel.

Thefnose 23 .is .extended upwardly fromY the reelrto Vpassbelzweenaar'pairof guiderollers 36 and through'an aperture in thelcover'plate 22 form'- ing the roof of the chamber 2|. At its free end the .-hose 42-3 `is provided with a fitting V3"! adapted t0 fbe coupled Vwith a complementary fitting 38 whichlatter isfconnected .with the pressure con'- nection Zilinthefbody ofthe aircraft. Connection 31 is provided :with a ilange 'adapted to be engaged :by a pair lof pivoted hook members-"39 which areactuable by Aa. vertically slidable'collar 40 through intermediate connecting links 4I. As will readily be seen from inspection of Figure 2, when the collar 40 is drawn upwardly the hook members 39 are released, thereby permitting disconnection of the coupling members 31 and 38.

Vertical movement of collar 40 is under the control of a hand lever 42 preferably positioned in the aircraft for convenient access by the pilot. The lever 42 is connected with a cable 43 which in turn is coupled with lever 44, pivoted as at 45, and having a forked end with pins engaging the collar 49. A spring 46 normally urges the collar 40 downwardly, thereby tending to maintain interengagement of the coupling members 31 and 38. The arrangement of the parts just described is preferably such that the coupling member 31 may automatically be disengaged from the coupling member 38 upon a substantial or excessive pull, as might occur toward the end of a takeo, the hook members 39 being forced outwardly against the force applied by spring 46.

The coupling member 31 is desirably of that known type which automatically closes upon disconnection from the cooperating coupling member 38. In this way loss of pressure fluid is avoided after the flexible transmission has been disconnected following a take-olf.

Certain automatic controls for the operation of the reel 24 are provided, for which purpose two swingingly mounted rollers 41 and 48 are positioned adjacent the hose 23 within the chamber 2 I. These rollers may appropriately be mounted on a standard 49. Roller 41 is so located as to be displaced toward the right (when viewed asin Figure 2) when the hose 23 is under tension, as, for instance, when the aircraft is taking-off and the hose is being extended. On the other hand, roller 48 is positioned to be engaged by the hose 23 when the latter is slackened, for instance, when the hose has been disconnected from the aircraft.

The rollers 41 and 48 are associated with contact or switch members 59 and 5l respectively, each of which upon being displaced is adapted to complete an electric circuit associated with the motor 29 for driving the reel. The circuit 52 which is associated with the switch 59 is adapted to complete the circuit in the motor windings in a manner providing for that direction of rotation which elfects paying-out of the hose 23. On the other hand, the circuit 53 associated with switch 5I provides for rotation of the motor 29 in that direction effecting reeling-in of the h'ose 23.

From the aboVe it will be seen that when the hose is under tension, the reel is rotated in a direction to pay-out the hose; and when the hose is slackened, the reel is rotated in that direction providing for reeling-in of the hose.

Circuit 53 is also associated with a circuit 53a with which switch or Contact member 54 cooperates, this switch being normally urged towards its position in which the circuit 53a is completed by means of a spring 55. Switch 54 is yadapted to be actuated by a ange 55 projecting from the coupling member 31. In this way whenever the hose is retracted or reeled-in, when the flange 58 of the coupling 31 abuts the switch member 54 the circuit 53a is broken thereby preventing further reeling-in of the hose, even if the switch 5I is in position to complete circuit 53.

In effecting a typical take-off with the system above described, the aircraft is brought into position, such as shown in Figure 1, in which the couplings 31 and 38 may be interconnected. This interconnection automatically provides for opening of the fluid passage in coupling* 81, so that uid under pressure is delivered through the pipe 20 and through the rotor blades to the jet reaction nozzles I9. At this time the pitch control for the rotor blades is desirably adjusted so that the mean pitch angle is at a low value, and the rotor accelerates. When an appropriate take-off R. P. M. has been attained the rotor blade pitch angle is increased and the machine rises from the ground substantially vertically as is indicated in chain dotted lines at the top of Figure 1. After an appropriate elevation has been attained, the pilot aotuates lever 42 to disconnect the coupling members 31--38, and the propulsive airscrews I2 are then employed to effect translational flight, rotation of the rotor being continued by the action known` in this art as autorotation.

Upon disconnection 0f the coupling member 31 from the aircraft, the hose 23 is slackened, thus becoming disengaged from roller 41 and engaging roller 48 as a result of which switch 5l is actuated to complete the circuit through the windings in motor 29, in a sense providing for ldriving the reel in a direction to effect reelingin of the hose 23. This reeling-in continues until the flange 56 of the coupling member 31 engages the switch 54 to break the motor circuit,

I thus terminating the reeling-in of the hose.

Another form of extensible and retractable uid pressure transmission is illustrated in Figures 4 to 'l inclusive. In this form it is contemplated thata standard 51 be mounted in the chamber below the landing surface, the standard serving to rotatively support an upright tubular member 58,`as by bearings 59 and 60. A fluid pressure supply line EI is coupled with' the lower end of the upright tube 58, as by means of a junction box 62 (see Figure 5) which desirably is arranged to remain stationary but to permit flow of pressure fluid from the supply line 6I to the pipe 58 even during rotation of the latter.

At a point above the bearing 59 a transversely extending connection 63 is arranged, which is adapted to receive fluid from pipe 58 and deliver the same to the downwardly inclined pipe B4, the latter delivering the pressure uid to the lower end of the telescopic assembly described just below.

A telescopic assembly preferably includes an internal flexible hose connection 65 with the upper end of which a coupling 31a is associated,

this coupling desirably being 'of the type described above in connection with the nrst form, and being adapted for cooperation with coupling 38 mounted on the aircraft adjacent the bottom Wall 8a thereof. The lower end of the hose con-Y nection is attached to a cylindrical member 56 adapted to slide in the surrounding tube 81, suitable packing tbeing interposed to prevent iluid leakage. Tube 61 is arranged to telescope within another tube 39, `appropriate packing 18 again being interposed to avoid fluid leakage.

As will be seen from Figure ,4, fluid is delivered from the connection 64 through an elbow 1I into the lower end of th'e external telescoping member 69 and from there into the inner telescoping tube 61 and ultimately to the innermost member 85.

The telescoping assembly is supported not only at itslower end (by means of elbow 1I) but also adjacent its upper end by an extension 58a of the upright rotatively mounted pipe 58. Still further, if desired, the telescoping assembly may be supported intermediate the upper and lower ends as by an extension 63a of the transverse pipe 83.

The:f.mounting-of the telescoping assembly, a-s above-described,,provides for freerotation thereofzaboutan'upright aXis, and Awith'the telescoped members inclined from the vertical, as 'shown in Flgure'fl, th'e unit will automatically adjust-itself about an upright axis to accommodate variations inthe flight path followed-by the aircraft in takingeoif, Making the final pressure connection 6.5"flexib1e also-aids in accommodating variations in flight path during take-off. l

In the system of Figure 4 it is contemplated that the ffluid transmission will automatically be extended by being lifted with the aircraft and that,.at least in large part, gravity will serve to retelescope theparts after the coupling member 31a has been disconnected from the aircraft. It will be understood that a pilot operable control means, such' as the lever 42 will also be employed inthe system 'of Figures 4 to '7, so that the pilot may eifect disconnection of the power transmission when the'desired altitude has been'fattained.

Iy claim:

`1. :A take-off vsystem for an aircraft having a sustaining rotor, comprising driving means associated with the rotor for driving the rotor for take-off, =an energy supply source on the ground, flexible transmission means for interconnecting said source :and .said aircraft and powering said drivin-g means, the said transmission means being disconnectible from the aircraft, and mechanism automatically operative on tensioning of the transmission means to effect paying out of the transmission means.

.-2.1A take-olf 'system for an aircraft having a sustaining'rotor,,comprising driving means associated with the rotor for driving the rotor for take-olf, an energy supply sourceon the ground, flexible .transmission means for interconnecting said source and said aircraft and powering said driving means, the said transmission means Ybeing disconnectible from Ythe aircraft, and mechanism automatically operative on slackening of thetransmission means to effect retraction ofthe transmission means.

v3, A take-off Asystem according to claim 1 wherein said paying out mechanism comprises a reel located on the ground, on which reel said transmission means is wound.

4. -A take-olf system according to claim 1 wherein there are means on the aircraft operativeto control said transmission means.

5. A take-olf system according to claim l whereinsaid driving means comprise expansiblegas jet-reaction equipment associated with the rotor, and wherein said transmission means comprises a fluid conveying tube and mechanism is provided for shutting `olf the fluid flow when the transmission means is disconnected from the aircraft.

`6. .A take-olf system according to claim 5 wherein the transmission means is quickly disconnectible while the aircraft is air-borne, and theshut-oif mechanism is constructed to be automatically operative upon such disconnection.

'1.1301' an aircraft .having a sustaining rotor and jet reaction means associated with the rotor for driving the rotor during take-off, the combination of a power source on the ground, flexible power transmission -means for interconnecting the power source and said reaction means, the power transmission means being disconnectable 8 from vthe aircraft, and means koperativenmder the iniluence of tensioning and fslackening' or' .the power transmission means for extending and retracting r'the power transmissionmeans.V

8. A construction according'to claim 57 iniwhich the power mechanism comprises flexible .ffluid pressure power transmission means.

9. A construction in accordancewith claim 7. in which vthe power transmissionmeans comprises a disconnectable fluid pressure connectionauto maticallyoperative to elect shut-onE thereof :upon being disconnected. Y

10. A construction in accordance witlyclaim. 7 and further including control meanson A.the aircraft for disconnecting the power transmission means, and in which said power transmission means includes a disconnectable uidpressure connection automatically operative to effect shutolf thereof upon being disconnected,

11.,For an aircraft having a sustaining rotor and driving means associated with therotor for driving the rotor during takeoff, the combination of a power source on the ground, flexible power transmission means for interconnecting-theV power source and the said driving means, the power transmission means being disconnectable from the aircraft, andmechanism automatically operative upon disconnectionof the power transmission means for reeling' in the` -power :trans-v mission means.

12. For an aircraft having aisustaining rotor and driving means associated with'the rotor for driving the rotor during take-olf, the combination of a power source on the ground, exible transmissionmeans for Ainterconnecting the power source and the said driving means, thepvpower transmission means being disconnectable from the aircraft, reversible' power reel means associated with the power transmission means, the reel means having control means operative under the influence of slaclrening of the transmission means to effect reeling in of the transmission means, and under tensioning of the'transmission means to effect paying out of thetransmission means.

13. -A construction in accordance with c1aim1-2 in which the reel means is electrically powered andthe control meanscomprises electrical vswitch means operative under the influence ofslackening of the transmission means to energize the reel power means in oneY direction of rotation and operative under the influence of tensioning lof the power transmission meansto energize the reel power means in the opposite direction Vof rotation.

- HAROLD F. PITCAIRN.

1.EFlERENCES` CITED The following references are of record in the file of this patent:

UNITED s'rATes PATENTS 

